re-set 'putor for bigger tires??

[shabbadoobie]

Hope this doesnt sound stupid but does the computer need to re-set after putting on larger tires? My Sporttrac had 30.5s originally & now has 33s--Just thought I'd ask. Thanks

 

[mdrut]

nope, you're good to go

 

[Alec]

did you change the speedo gear? if not, you're odo and speedo are all reading wrong.

 

[EB2K]

the new xplorers dont have speedo gears, just computer stuff. or at least that is what ive been told.

 

[Robert]

That is correct for at least '99 on up. We never resolved whether or not '98s had a speedometer gear. My '97 does have a speedometer gear. To reprogram his speedometer on his '01 SportTrac it will take a computer hooked up to his to reprogram it.

 

[jwild4x4]

I just moved up to 31x10.5's from p235/75/R15's. Doesn't it make sense that you should reset your computer now? I'm debating whether to reset mine. With larger tires, the Engine RPMs are now lower for a given speed. Shouldn't the computer be reset to account for differences? I know that reseting won't affect my spedo, but I thought that the computer would "like" to relearn the difference in ratio of RMP's to vehicle velocity??? Does this make sense or am I being stupid? Thanks

Jason

 

[Robert]

I don't know about that, but it can't hurt. You should put a new speedometer gear in it though. I think you need one with one less tooth than you take out.

 

[Fantasymon]

I have a 2000. Stock tires were 235/75/15. Now put 265/70/17. The new tires are 31.8"in diameter and the stocks were 29".

I cant decide whether or not I should pay $75 + to have my computer reprogrammed.

I drove today next to my friend. We used cell phones and when he was goin 59 my speedo also read 59. But when he got up to 75, my speedo read 70.

I guess my speedo isnt off too much. Also I am guessing that my odometer will slightly read less miles than I have after a while. (which is pretty cool)

Do you think I should pay to have it reprogrammed? Kinda low on cash..

Thanks
Grant-P